Typeinheritanceisthatphenomenonaccordingtowhichwecansay,forexample,thateverysquareisalsoarectangle,andsopropertiesthatapplytorectanglesingeneralapplytosquaresinparticular.Inotherwords,squaresareasubtypeofrectangles,andrectanglesareasupertypeofsquares.Recognizingandactinguponsuch